Venomous animals – gland or glands which produces the venom and a Connecting system between gland and delivery apparatus.

Venom delivery is not "all or nothing", but rather is graded and their purposes are 1).

Capture and digestion of food, and 2). Offers protection against predators

Toxicity of venom and poison

The LD50 for any particular venom will vary, depending on:
- The type of animal it is tested in
- The route of injection
- The way the venom is prepared for injection
- Variability in both toxicity and composition of venom, both within a single animal, between animals of the same species